We have been focusing on recruiting older patients with chromosome 22q11.2 deletion syndrome into the study because there is a paucity of knowledge about this group. Our initial studies have suggested premature immunologic senescence in chromosome 22q11.2 deletion syndrome. This was based on the study of 12 people over the age of 6 years with this syndrome. Characteristic findings included inversion of CD4/45RA to CD4/45RO ratio, lymphopenia, and decreased proliferative responses. These are all typically seen in normal controls over the age of 50. The significance of these findings is uncertain. Senescence in normals is associated with decreased ability to respond to immunizations and difficulty in controlling infections. If this turns out to be true for this relatively chronologically young population, one would expect a significant healthcare burden as a result. Our future plans include recruiting additional patients for further characterization of the immunodeficiency in this group and performing additional studies to confirm that this immunologic decline is related to the process of senescence.